Chloe, if your parts have intricate features then soaking your part in 2% caustic soda for two hours will help loosening up the support structure. It also removes the last thin layer that you will be unable to sand off. Alcohol is for drying the part.
If you go for an ultrasonic cleaner, the ones from China do not do much so buy a good one.
Also, there is now a new material, Agilus30, for many applications superior to TangoBlack.